For a power source circuit that outputs a bandgap reference voltage, a configuration that includes a circuit that outputs a signal that indicates that the bandgap reference voltage is output has conventionally been known. A bandgap reference voltage is used as a reference voltage of a series regulator, a DC/DC converter, or the like. In a case where a signal is output that indicates that a bandgap reference voltage is output even though it is not provided in a desired state, a circuit that receives a voltage from a power source circuit to operate is caused to operate erroneously. Hence, it is desired that a signal that indicates being output is a signal that accurately reflects a state of a bandgap reference voltage that is output by a power source circuit.